1. Field of the Invention
The present invention relates to a logic semiconductor integrated circuit device having an embedded dynamic random-access memory (referred to hereafter simply as a DRAM), wherein a DRAM is embedded in a semiconductor integrated circuit device having a special function built from functional blocks known as a macrocell comprising logic circuits.
2. Background Art
In recent years, a variety of semiconductor integrated circuit devices have been provided, accompanying the increasing scale of integration of semiconductor integrated circuits.
In particular, a semiconductor integrated circuit device built by combination of a memory having a large momory capacity and logic or, to put it concretely, a logic semiconductor integrated circuit device having an embedded DRAM wherein the DRAM and logic are embedded in one chip and connected to each other by buses to allow a large amount of data to be processed at a high speed turns out to be a highlighted product which draws much attention.
In such a logic semiconductor integrated circuit device having an embedded DRAM, the DRAM and logic portions are formed separately on a single substrate. In general, the DRAM and logic portions are connected to each other by buses.
In such a logic semiconductor integrated circuit device having an embedded DRAM wherein the DRAM and logic portions are laid out in areas completely separated from each other in a single chip, however, there are restrictions imposed on the layout and the size (or the momory capacity) of the DRAM portion, raising a problem that the logic semiconductor integrated circuit device having an embedded DRAM has a lack of freedom to lay out components thereof and that it is difficult to change the size of the chip.
In addition, when it is necessary to change the number of bits of data output from the DRAM portion, that is, when it is necessary to change the width of a data bus, internal circuits of the DRAM portion need to be modified and/or corrected, giving rise to a problem that it takes time to implement changes in design of the internal circuits.